Ulster Unionists and the SDLP may decline seats in a restored Stormont executive, senior figures in both parties have suggested.
Mr David Trimble said his party had not decided its stance, but would await the return of powers before choosing whether they would form an opposition with the SDLP within the Assembly.
Mr Alban Maginness said last night the possibility of refusing executive places was being "actively considered" by the SDLP. Like the UUP, he said the issue would be decided when the party saw the circumstances in which power was restored.
Mr Trimble, taking reporters' questions at his Belfast headquarters yesterday, said: "Any decision about what we do in the event of devolution will be taken when devolution occurs.
"I haven't made my mind up myself; I don't think it is right even to think about it other than as an academic exercise until we see the circumstances."
He called for those inside the UUP with fixed views about adopting some form of opposition role in any restored Assembly to halt their speculation until the circumstances permitting restoration of the Assembly were clear.
Some UUP Assembly members have said privately they support the refusal to take seats in any new executive, and to sit in opposition to a Sinn Féin-DUP executive.
Mr Maginness said the SDLP would wait to see what form devolution would take following talks between the parties and the two governments.
Referring to an announcement by the DUP deputy leader, Mr Peter Robinson, to consider talks with loyalist paramilitary representatives, Mr Maginness asked: "Is this sudden shift of attitude motivated by their hunger for power? Is the DUP perhaps softening up the hard edge of its own constituency to prepare it for two-party coalition with Sinn Féin?"
The Alliance party was also dismissive of Mr Robinson's remarks.
Ms Eileen Bell, deputy leader, said: "It would be the ultimate in hypocrisy if the DUP were now to talk officially to the PUP and UPRG yet refuse to engage with Sinn Féin.
"How could the DUP ignore Sinn Féin when the IRA has gone further towards 'going out of business' than any of the loyalist paramilitary groups?"
Mr Trimble said he was unsure what to make of remarks by the Minister for Foreign Affairs concerning the possibility of Sinn Féin helping to form a future coalition in the Republic.
He said Mr Dermot Ahern, like others at the Department, had a tendency to "talk things up" as a means of trying to encourage Sinn Féin.
Mr Trimble said the UUP hoped for an early meeting with Mr Ahern to discuss the issue and to seek "clarification".